"If people are prepared to make a public declaration to each other in front of their friends and family they are more likely to stay together. Without marriage people drift in and out of relationships very easily," he said.

"In families where parents break up children do less well at school, are more likely to suffer mental health problems and are more likely to have substance abuse problems.

"The government needs to send a very clear message that it supports marriage. That's why married tax breaks are so important."